Methods for using front-loading medical fluid injector

ABSTRACT

Various sealing structures are used in a front-loading injector, for preventing leakage of spilled fluid from an external surface of a syringe into the vicinity of the drive ram. For example, a sealing gasket may be incorporated into the front face of the injector housing, for mating to the rearward circular edge of the cylindrical body of a syringe. Alternatively, sealing and locking functions may be performed by a single structure on the rearward end of the syringe. Further, leakage may be prevented by including a non-planar sealing flange on the syringe, positioned on the syringe forward of the locking structure, or by a two-piece structure, including a syringe and a separate leakage stopping washer for surrounding the syringe to halt the flow of fluid along the exterior of the syringe. (As part of this aspect, or as an independent feature, the syringe may include an annularly discontinuous flange forward of the locking structure, for providing mechanical support for the syringe against the injector.) Alternatively, an iris-like structure may be incorporated into the front surface of the injector, for closing about the syringe upon insertion of the syringe into the injector.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of:

co-pending U.S. patent application Ser. No. 11/458,463 filed 19 Jul.2006, which is a division of U.S. Pat. No. 6,569,127, filed 20 Sep.2000, which is a continuation of now abandoned U.S. patent applicationSer. No. 08/896,695 filed 18 Jul. 1997;

U.S. patent application Ser. No. 11/420,664 filed 26 May 2006, nowabandoned, which is a division of U.S. Pat. No. 6,569,127, filed 20 Sep.2000, which is a continuation of now abandoned U.S. patent applicationSer. No. 08/896,695 filed 18 Jul. 1997;

U.S. patent application Ser. No. 10/386,957 filed 12 Mar. 2003, nowabandoned, which is a division of U.S. Pat. No. 6,569,127, filed 20 Sep.2000, which is a continuation of now abandoned U.S. patent applicationSer. No. 08/896,695 filed 18 Jul. 1997;

the entire disclosures of which are hereby incorporated by reference.

Further, this application is related to U.S. patent application Ser. No.11/677,926, entitled SPRING LOADED MEDICAL FLUID INJECTOR ASSEMBLY,filed on even date herewith, which claims the same priority as above.

FIELD OF THE INVENTION

The present invention relates to medical fluid injectors for injectingmedical fluid into patients.

BACKGROUND OF THE INVENTION

Injectors are devices that expel fluid, such as contrast media, from asyringe and through a tube into an animal. An injector often includes aninjector unit, usually adjustably fixed to a stand or support, which hasa drive ram that couples to the plunger of a syringe to drive theplunger forward to expel fluid into the tube, or to drive the plungerrearward to draw fluid into the syringe to fill it. Usually the syringeis disposable.

U.S. Pat. No. 5,300,031, which is assigned to the same assignee as thisapplication, discloses a front-loading injector, and is incorporated byreference herein in its entirety. This injector has a pressure jacketmounted to its front face for receiving a syringe. A syringe having anopen back end is inserted into the pressure jacket, and an umbrellasurface on the front of the syringe, is coupled to the pressure jacketby a rotating motion. This same rotating motion causes the plunger inthe syringe to couple to the end of the ram. The pressure jacketsupports the side walls of the syringe against injection pressure duringoperation of the injector. After an injection, a reverse rotating motionunlocks the syringe from the pressure jacket and releases the plungerfrom the ram, so the syringe can be removed and replaced.

A second front-loading injector structure is disclosed in U.S. Pat. No.5,383,858, which is also incorporated by reference herein in itsentirety. This front loading injector structure is similar in manyrespects to that disclosed in U.S. Pat. No. 5,300,031, with the maindifference that the injector of the primary figures (FIGS. 1-8) of U.S.Pat. No. 5,383,858, does not include a pressure jacket on the frontsurface thereof. Rather, the syringe is made of a hard plastic materialwhich is deemed sufficiently self-supporting to withstand injectionpressures. In the front-loading injector of U.S. Pat. No. 5,383,858, thesyringe and injector, and the plunger and ram, are connected to eachother by a single twisting motion, and disconnected from each other by areverse twisting motion; thus, the connection and disconnectionprocedures are similar to that used by the injector of U.S. Pat. No.5,383,858.

Both of the above-noted U.S. Patents show syringes incorporating lockingstructures for locking the syringe to the front surface of the injector,as well as a disc-like, annular sealing flange for contacting andsealing to an annular edge on the front surface of the injector or itspressure jacket. This annular sealing flange prevents contrast media orany other injectable fluid which might flow along the outside of thesyringe, from leaking into the area where the ram exits the injector,and potentially fouling the mechanical systems inside of the injector.

SUMMARY OF THE INVENTION

There are several disadvantages to including an annular disc-likesealing flange on the syringe. This disc-like flange can be difficult tomold, and when molded to a sufficient thinness to permit a sealing,interference fit with the front face of the injector, can be fragile andsubject to breakage. Accordingly, there is a need for a front-loadinginjector and syringe which does not require the inclusion of a disc-likesealing flange on the syringe.

In accordance with a first aspect of the present invention, this need ismet by an injector including an annular, sealing gasket incorporatedinto the front face of the injector housing, for mating to the rearwardcircular edge of the cylindrical body of a syringe. A locking structureon the outer surface of the syringe and the face of the injector, holdsthe syringe in tight sealing contact with the gasket on the face of theinjector, preventing leakage from the outside surfaces of the syringeinto the vicinity of the drive mechanism of the injector.

In specific disclosed embodiments of this aspect of the invention, thelocking structure on the outer surface of the syringe comprises one ormore radially extending members, which mate to one or more radiallyextending members on the face of the injector. The members on the faceof the injector may be radially disposed tabs, for receiving flanges onan outer surface of the syringe. The flanges on the syringe are rotatedinto and out of engagement with the tabs on the face of the injector.The tabs on the injector may form a radially outwardly-facing groove,for receiving a radially inwardly-facing flange on the syringe, oralternatively, the tabs on the injector may have a radiallyinwardly-facing groove, for receiving a radially outwardly-facing flangeon the syringe.

In a second specific embodiment, the face of the injector may include aslot, for receiving the radially-outwardly extending members on thesyringe, by sliding the syringe transversely to its axis, intoengagement with the injector. As a third alternative, the face of theinjector may include a rotating turret, for engaging radially-outwardlyextending members on the syringe, and rotating the syringe transverselyrelative to its axis, into registration with the drive mechanism on theinjector.

In accordance with a second aspect of the present invention, the sealingfunction is provided by incorporating sealing and locking functions intoa single structure on the rearward end of the syringe. Specifically, theend of the syringe includes a radially outwardly-extending sealingstructure, which includes integral locking members for engaging matingstructures on the face of the injector.

In specific disclosed embodiments of this aspect, these locking membersform a channel in the sealing structure on the syringe, for receivingtabs on an interior surface of the injector housing, so that the sealingstructure may be inserted into the housing and rotated to lock thesyringe to the injector.

In accordance with another aspect of the present invention, leakage isprevented by including a non-planar sealing flange on the syringe,positioned on the syringe forward of the locking structure. In specificembodiments of this aspect, the non-planar sealing flange includes acusp feature for diverting fluid flowing along the surface of thesyringe.

In yet another aspect of the present invention, leakage is prevented bya two-piece structure, including a syringe and a separate leakagestopping washer for surrounding the syringe to halt the flow of fluidalong the exterior of the syringe.

A separate unique feature of this aspect of the invention, is thestructure of the syringe, which includes an annularly discontinuousflange forward of the locking structure, for providing mechanicalsupport for the syringe against the injector. This discontinuous flangenot only provides mechanical support for the syringe when mounted to theinjector, but also aids in positioning the leakage stopping washer,which when installed abuts against the annularly discontinuous flange.

In accordance with another aspect of the present invention, leakage isprevented by an iris-like structure on the front surface of theinjector. The iris-like structure includes mechanical actuators forclosing the iris-like structure about the syringe upon insertion of thesyringe into the injector, thus forming a seal between the syringe andinjector.

In specific embodiments of this aspect, the mechanical actuatorsinteract with locking flanges on the rearward surface of the syringe,for translating the iris-like structure into engagement of the syringeupon rotation of the locking flanges on the syringe into the mechanicalactuators.

The above and other objects and advantages of the present inventionshall be made apparent from the accompanying drawings and thedescription thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a perspective view of a first embodiment of a syringe and areplacement face plate for the injector described in U.S. Pat. No.5,383,858;

FIG. 2 is a cross-sectional view taken on line 2--2 of FIG. 1, of thesyringe and injector of FIG. 1 when coupled together;

FIG. 3 is a perspective view of a second embodiment of a syringe and areplacement face plate for the injector described in U.S. Pat. No.5,383,858;

FIG. 4 is a perspective view of a third embodiment of a syringe and areplacement face plate for the injector described in U.S. Pat. No.5,383,858;

FIG. 5 is a perspective view of a fourth embodiment of a syringe andreplacement face plate for the injector described in U.S. Pat. No.5,383,858;

FIG. 6 is a perspective view of a fifth embodiment of a replacementsyringe for the injector described in U.S. Pat. No. 5,383,858;

FIG. 7 is a perspective view of a sixth embodiment of a replacementsyringe for the injector described in U.S. Pat. No. 5,383,858;

FIG. 8 is partial cut-away front view of a seventh embodiment of areplacement face plate for the injector described in U.S. Pat. No.5,383,858, showing a sealing mechanism in an open position for receivinga syringe;

FIG. 9 is a view similar to FIG. 8, showing the sealing mechanism in aclosed position as a result of a syringe being mounted thereto;

FIG. 10 is a cross-sectional view taken on line 10--10 of FIG. 8, of theactuating mechanism incorporated in the face plate of FIGS. 8 and 9;

FIG. 11 is a partial cut-away front view of an eighth embodiment of areplacement face plate for the injector described in U.S. Pat. No.5,383,858, showing a sealing mechanism in an open position for receivinga syringe;

FIG. 12 is a view similar to FIG. 11, showing the sealing mechanism in aclosed position as a result of a syringe being mounted thereto.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring now to FIG. 1, in accordance with a first embodiment of thepresent invention, the injector disclosed in U.S. Pat. No. 5,383,858 isoutfitted with a replacement face plate 10, incorporating features formounting a syringe 12. Face plate 10 includes an opening 11 at a centrallocation thereof. The syringe drive ram 13 of the injector extendsthrough opening 11 to engage the plunger of a syringe mounted to faceplate 10, by a relative rotational motion of the plunger and ram, in themanner described in U.S. Pat. No. 5,383,858. Surrounding opening 11 is acircular gasket 15 of a flexible material such as rubber.

The structure of syringe 12 is notable in that it does not include adisc-like sealing flange on its exterior. Rather, the exterior surfaceof cylindrical barrel 14 of the syringe is smooth but for two lockingflanges 16 a and 16 b extending from the rearward end of the syringe.The syringe also includes, as is conventional, a plunger 19 sealinglyengaging an interior of cylindrical barrel 14 and sliding within barrel14 between an open rearward end of barrel 14 and a closed forward end18. Forward end 18 terminates in a discharge extension 20, to whichtubing is mounted to carry injected fluid to a patient. A rearwardsurface of plunger 19 includes flanges 21 a and 21 b similar to thosedescribed in U.S. Pat. No. 5,383,858, for engaging head 17 of plungerdrive ram 13.

Flanges 16 a and 16 b on syringe 12 are matable to locking structures 22a and 22 b, respectively, on the front face of face plate 10.Specifically, face plate 10 includes radially outwardly-extending tabs24 a and 24 b, which form radially outwardly-facing grooves 26 a and 26b which extend partially annularly about opening 11 in face plate 10.Locking flanges 16 a and 16 b on the rearward end of syringe 12, includeradially inwardly-extending tabs 28 a and 28 b positioned to interlockinto grooves 26 a and 26 b behind tabs 24 a and 24 b.

Referring now to FIGS. 1 and 2, in this embodiment, a syringe isinstalled onto injector by first translating the syringe along its axisin the orientation shown in FIG. 1, until the rearward circular edge 30of cylindrical barrel 14 of the syringe, engages gasket 15 surroundingopening 11 in face plate 10. Then, syringe 12 is rotated clockwise toguide tabs 28 a and 28 b on the rearward end of syringe 12 into grooves26 a and 26 b on face plate 10. When syringe 12 is rotated ninetydegrees clockwise, tab 28 a engages stop 32 a at the end of groove 26 a,thus preventing further clockwise rotation of syringe 12. (Another stop32 b, is incorporated at the clockwise end of groove 26 b.) Thus, wheninstalling a syringe, the syringe is rotated clockwise for approximatelyninety degrees until further rotation is impossible, at which point theuser can be certain that the syringe is fully installed.

To facilitate installation of a syringe to face plate 10, the diameterof locking structures 22 a and 22 b may be slightly reduced at theircounter-clockwise ends, to facilitate mating of the syringe lockingstructures 16 a and 16 b to flanges 22 a and 22 b on face plate 10. Inaddition, the thickness of tabs 24 a and 24 b may be reduced at theircounter-clockwise ends (e.g., to the thickness shown in hidden lines at31 a and 31 b), to facilitate mating of the syringe locking structuresto tabs 24 a and 24 b and to tighten the rearward circular edge 30 ofsyringe 12 against gasket 15 as the syringe is rotated clockwise intoposition. Furthermore, small buttons and detents, or other features, maybe incorporated into locking structures 16 a and 16 b and/or flanges 22a and 22 b, placed so as to interact and provide audible and/or tactilefeedback to a user installing a syringe onto face plate 10, so the userknows when the syringe is properly positioned.

As is visible in FIG. 2 in particular, ninety-degree rotation of syringe12 into engagement with face plate 10, also causes flanges 21 a and 21 bon plunger 19 to engage head 17 on plunger drive ram 13, so that plungerdrive ram 13 can thereafter drive plunger 19 forward and rearward withinthe cylindrical barrel 14 of the syringe, to perform an injection.

Also visible in FIG. 2, is the interaction of the rearward surface 30 ofsyringe 12, and gasket 15. When syringe 12 is fully installed to faceplate 10, gasket 15 is partially compressed against rearward surface 30of syringe 12, so as to form a seal therewith. This seal reduces leakageof injection fluid from the exterior surface of the barrel 14 of syringe12, into the area where drive ram 13 exits from face plate 10. Thisgasket provides the functions provided by the disc-shaped sealing flangedescribed in the above-noted U.S. Patents, without requiring complexmanufacturing or involving breakable parts.

It will be appreciated that alternative forms of locking structure maybe used to mount syringe 12 to face plate 10. For example, tabs 24 a, 24b on the face plate 10 may form an inwardly-facing groove such as thegroove (23 s) shown in the main figures (FIGS. 1-8) of U.S. Pat. No.5,383,858 in particular, for mounting to outwardly-projecting structureson syringe 12. In one specific embodiment, the outwardly-projectinglocking structures 16 a and 16 b on the rearward end of syringe 12 aresized so as to be insertable into the inwardly-facing groove 23 s of theinjector described in U.S. Pat. No. 5,383,858, so that syringe 12 may bemounted without modification to the injector of U.S. Pat. No. 5,383,858,or may be mounted to the substitute face plate 10 shown in FIGS. 1 and2.

Referring now to FIG. 3, a third alternative locking structure can bedescribed. In this alternative, a replacement face plate 33 includesradially inwardly-extending tabs 34 which form an inwardly-facing slot36 for gripping locking structure on the rearward end of the syringe 12.In this embodiment, syringe 35 may be mounted by sliding the syringetransversely to its axis, into slot 36 and engagement with tabs 34. Thelocking structure on the rearward end of syringe 35 may include a numberof tabs such as are shown in FIGS. 1 and 2, or may be a continuous,annular flange 38 such as is shown in FIG. 3.

It will be appreciated that the face plate 33 shown in FIG. 3 includes agasket 15 identical in function and placement to the gasket 15 discussedabove with reference to FIGS. 1 and 2. Gasket 15 forms a seal with therearward surface of syringe 35, to form a seal therewith to inhibit theflow of fluid from the exterior of syringe 35 into the regionsurrounding plunger drive ram 13.

In the embodiment of FIG. 3, flanges 21 a and 21 b on plunger 19 aresimilar to those described above and in U.S. Pat. No. 5,383,858, and arecoupled to head 17 of plunger drive ram 13 by rotating syringe 12 aftersyringe 12 has been fully inserted into slot 36 on face plate 33. Othercoupling structures could also be used, including, for example, adisk-shaped end on drive ram 13, for engaging flanges 21 a and 21 b uponlateral translation of syringe 35 into slot 36 on face plate 33, withoutrequiring rotation.

It will be appreciated that keyed features might be included into slot36 and/or flange 38 to require that syringe 35 be placed in a properrotational orientation before syringe 35 can be slid into slot 36. Forexample, the opening of slot 36 may be slightly narrower than the widestdiameter of flange 38, and flange 38 might include a flat which must beoriented properly for flange 38 to pass through the narrowed opening ofslot 36 and into a mounted position.

Referring now to FIG. 4, a second alternative structure for mounting asyringe to an injector is shown. In this alternative, face plate 39incorporates a turret 40. Turret 40 includes two jaws 42 a and 42 b intowhich one or two syringes can be inserted. The syringe 41 is similar tothe syringe shown in FIG. 3, in that it includes a continuous, annularflange 43 at its rearward end. As before, a gasket (not shown) isincorporated into face plate 39, surrounding the opening through whichthe plunger drive ram emerges from the injector, so that the rearwardsurface of syringe 41 forms a seal therewith to inhibit leakage ofspilled fluid into the internal mechanisms of the injector.

Referring now to FIG. 5, a second type of syringe-injector sealingstructure can be discussed. The injector has a replacement face plate48, for mounting a syringe 50. Syringe 50 includes a single-piece,combination locking and sealing structure 54 at its rearward end.Structure 54, which has a conically-shaped outer surface, has twochannels 56 a and 56 b molded therein. Each channel 56 a and 56 bincludes an axial opening portion (57 a in channel 56 a, not shown inchannel 56 b) and an annular portion (59 a in channel 56 a, 59 b inchannel 56 b). Face plate 48 includes a conically-shaped opening 58surrounding injector drive ram 13, which is matable to theconically-shaped outer surface of structure 54 on the rearward end ofsyringe 50. Within opening 58 are tabs 60 positioned annularly about aninterior of opening 58 and sized to fit into the axial opening portionsof channels 56 a and 56 b of syringe structure 54. A gasket (not shown)may also be incorporated into the rim of opening 58 forward of tabs 60for sealing purposes.

Syringe 50 is installed into injector face plate 48 by insertingstructure 54 at the rearward end of syringe 50 into opening 58, withtabs 60 aligned with the axial opening portions of channels 56 a and 56b, and then rotating syringe 50 clockwise over an angle of approximatelyninety degrees, thus locking tabs 60 into the annular portions 59 a and59 b of channels 56 a and 56 b. Once locked to face plate 48, a seal isformed between syringe 50 and face plate 48 which inhibits flow ofspilled fluid from the exterior of syringe 50 into the mechanism ofdrive ram 13.

Referring now to FIG. 6, in accordance with a further embodiment of thepresent invention, a syringe such as that shown in U.S. Pat. No.5,383,858 can be improved by enhancing the rigidity of the sealingflange. Specifically, the sealing flange can be made non-planar, e.g.,as shown in FIG. 6, the sealing flange 64 may be formed with acusp-shaped feature 66, thus enhancing the rigidity of the flange whilecontinuing to guide spilled fluid flowing rearwardly along the exteriorof the syringe away from the drive mechanism. The non-planar sealingflange shown in FIG. 6 thus provides the leakage protection function ofthe planar flange shown in U.S. Pat. No. 5,383,858. U.S. Pat. No.5,383,858 further indicates that the sealing flange described in thatpatent stabilizes the syringe while mounted to the injector. Thisfunction is also provided by the sealing flange 62 shown in FIG. 6 inthat there are substantial annular portions of sealing flange 62 whichcontact the sealing rim on the injector shown in U.S. Pat. No.5,383,858, lending the needed stability.

Referring now to FIG. 7, in accordance with a further embodiment, asyringe 68 for mounting to the injector described in U.S. Pat. No.5,383,858, includes an annular sealing flange which is annularlydiscontinuous, i.e., separated into segments such as 70. An annularlydiscontinuous flange, while not necessarily accomplishing the sealingfunction described in U.S. Pat. No. 5,383,858, does provide stabilityfor the mounted syringe, in that segments 70 contact and form aninterference fit with the face of the injector. (The placement ofsegment 70, and additional segments 72, can be determined based on thestability needed.) Furthermore, the annularly discontinuous segments 70,can perhaps be made of more thick layers of plastic, since the gapsbetween the segments make the segments more able to flex than anannularly continuous flange. Moreover, an annular flange formed insegments may be more easily molded than an annularly continuous flange.

To provide a sealing function, particularly in connection with syringeshaving an annularly discontinuous sealing flange, but also in otherapplications, a leakage stopping washer 74 may be provided inconjunction with the syringe. Washer 74 may be formed of solid rubber,sponge rubber, paper or any other absorbent and/or sealing material.Washer 74 may be disposable, and sold with syringe 68 for one-time use,or may be reusable. In either case, washer 74 is slipped over thecylindrical barrel 76 of syringe 68. Washer 74 is made of an elasticmaterial and is formed with a slight interference fit relative to thecylindrical barrel 76 of syringe 68, so that washer 74 forms a seal withbarrel 76 to inhibit leakage past washer 74. In one embodiment, flangesegments 70 are used to position washer 74 at the rearward end ofsyringe 68 so that washer 74 is opposite to the face of the injectorwhen syringe 68 is installed on the injector. In other embodiments,washer 74 may be positioned at any other location along the cylindricalbarrel 76 of syringe 68.

Referring to FIG. 8, in accordance with a further embodiment, a sealingfunction may be provided by an iris-like structure on a face plate ofthe injector, for closing about the syringe to provide a seal betweenthe face plate and outer barrel of the syringe. As seen in FIG. 8, thesyringe 78 includes a cylindrical barrel 80, and locking flanges 82projecting from barrel 80 adjacent a rearward end of the syringe. Thus,the structure of the syringe is similar to that of the syringe shown inU.S. Pat. No. 5,383,858, with the annular sealing flange removed.

The syringe 78 is mounted into an opening in a replacement face plate 86mounted on the front face of the injector. An opening 88 in the faceplate permits the plunger drive ram 13, and in particular theplunger-mounting head 17 thereof, to emerge from the injector and engageand drive the plunger within the syringe. Face plate 86 further includesannular grooves of the kind illustrated in U.S. Pat. No. 5,383,858, sothat locking flanges 82 of a syringe may be inserted into the face plate86 in the orientation shown in FIG. 8, and then rotated into a lockedposition on the face plate.

As seen in FIG. 8, in addition to the structures described above, faceplate 86 includes two sealing arms 90 a and 90 b which, in the openposition illustrated in FIG. 8, permit locking flanges 82 of a syringeto pass into the face plate for locking to the face plate. Sealing arms90 a and 90 b are arcuate sections, having an inside radius of curvaturealong edges 92 a and 92 b which is approximately equal to the radius ofthe cylindrical wall 80 of the syringe 78.

Referring now to FIGS. 8 and 9, the motion of sealing arms 90 a and 90 bfrom their open position of FIG. 8 to their closed position of FIG. 9can be illustrated. Specifically, when a syringe is inserted into faceplate 86 in the orientation shown in FIG. 8, and then turned clockwiseto the orientation shown in FIG. 9, this rotational motion causessealing arms 90 a and 90 b to similarly rotate clockwise from the openpositions shown in FIG. 8 into the closed positions shown in FIG. 9. Ascan be seen in FIG. 9, in their closed positions the interior edges 92 aand 92 b of sealing arms 90 a and 90 b engage the outer cylindrical wall80 of the syringe and form a seal therewith, thus inhibiting leakage ofspilled fluid along the wall of the syringe. (The interior edges 92 aand 92 b of sealing arms 90 a and 90 b may carry rubber or otherflexible seals such as are shown at edges 92 a and 92 b illustrated inFIG. 10.) At the same time sealing arms 90 a and 90 b lend mechanicalstability to the syringe when it is mounted on the injector face plate86.

Now referring to FIGS. 8, 9 and 10, in the illustrated embodiment,rotation of arms 90 a and 90 b is generated through mechanicalmechanisms including a lever arm 94, which drives a pinion gear 96,which meshes with a main gear 98 rotationally coupled to the sealing arm90. Clockwise rotation of the syringe from the position shown in FIG. 8to the position shown in FIG. 9, causes locking flange 82 of the syringeto engage and rotate lever arm 94 counterclockwise. Counterclockwisemotion of lever arm 94 causes counterclockwise motion of pinion gear 96.Pinion gear 96, meshing with main gear 98, causes main gear 98 to rotateclockwise, driving the connected sealing arm to rotate clockwise to itsclosed position.

As shown in FIG. 10, main gear 98 is rotationally locked to a shaft 100,which passes through face plate 86 and into sealing arm. Thus, rotationof main gear 98 causes rotation of shaft 100 and corresponding rotationof sealing arm 90 b. A torsion spring 102 coupled between main gear 98and face plate 86 produces a return force tending to rotate main gear98, shaft 100 and sealing arm 90 counterclockwise to an open positionwhenever the syringe is rotated counterclockwise toward its disengagedposition.

Referring to FIGS. 11 and 12, in an alternative embodiment, sealing arms101 a and 101 b translate laterally between their open and closedpositions, to provide a sealing function when a syringe is installed tothe injector. The syringe used in this embodiment is similar to thatused in the embodiment of FIGS. 8, 9 and 10. However, sealing arms 101 aand 101 b are different in structure. Sealing arms 101 a and 101 binclude, on their rearward faces, channels 103 a and 103 b, forreceiving pins 104 a and 104 b on the face plate 105 of the injector.Sealing arms 101 a and 101 b translate laterally with respect to theaxis of the syringe, such that pins 104 a and 104 b slide withinchannels 103 a and 103 b, guiding the motion of arms 101 a and 101 b.Motion is imparted to sealing arms 101 a and 101 b by lever arms 106 aand 106 b, respectively, which pivot about axes 107 a and 107 b,respectively. Lever arms 106 a and 106 b include pins 110 a and 110 b attheir exterior ends, which are received into channels 108 a and 108 b onthe rearward faces of sealing arms 101 a and 101 b. Counterclockwiserotation of lever arms 106 a and 106 b causes pins 110 a and 100 b tointeract with channels 108 a and 108 b to drive sealing arms 101 a and101 b to the closed positions shown in FIG. 12. Clockwise rotation oflever arms 106 a and 106 b causes pins 110 a and 100 b to interact withchannels 108 a and 108 b to drive sealing arms 101 a and 101 b to theopen positions shown in FIG. 11.

Insertion and rotation of a syringe into a locked position in face plate105, causes rotation of lever arms 106 a and 106 b to close sealing arms101 a and 101 b. Specifically, a syringe is inserted with lockingflanges 82 in the positions shown in FIG. 11. Next, the syringe barrel80 is rotated clockwise approximately ninety degrees, from theorientation shown in FIG. 11 to the orientation shown in FIG. 12. Thisrotation causes locking flanges 82 to engage ends 112 a and 112 b ofsealing arms 101 a and 101 b, causing counterclockwise rotation oflevers 106 a and 106 b about axes 107 a and 107 b, thus bringing sealingarms 101 a and 101 b to their closed positions shown in FIG. 12.

Counterclockwise rotation of the syringe to unlock it from face plate105, opens sealing arms 101 a and 101 b to permit the syringe to beremoved. Specifically, torsion springs such as 114 a and 114 b on eachlever 106 a and 106 b, exert a force upon levers 106 a and 106 b to urgelevers 106 a and 106 b to rotate clockwise. Thus, when the syringe isrotated so that locking flanges 82 no longer interact with ends 112 aand 112 b of levers 106 a and 106 b, levers 106 a and 106 b rotateclockwise, opening sealing arms 101 a and 101 b to the positions shownin FIG. 11, so that the syringe may be removed.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The invention in its broader aspects istherefore not limited to the specific details, representative apparatusand method, and illustrative example shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of applicant's general inventive concept.

What is claimed is:
 1. A method of using a front-loading, medical fluidinjector, the method comprising: rotating a syringe relative to theinjector, wherein the rotating is accomplished in opposition to a springforce provided by the injector; and moving an arcuate section of asyringe mounting mechanism of the injector relative to a housing of theinjector, wherein the moving is due, at least in part, to the rotating,wherein the arcuate section of the syringe mounting mechanism movestoward the syringe due to rotation of the syringe in a first directionand away from the syringe due to rotation of the syringe in a seconddirection substantially opposite the first direction.
 2. The method ofclaim 1, wherein the syringe mounting mechanism comprises an iris-likestructure.
 3. The method of claim 2, wherein the moving comprises movingfirst and second arms of the iris-like structure relative to the housingof the injector, wherein the first arm of the iris-like structurecomprises the arcuate section.
 4. The method of claim 1, wherein themoving comprises pivoting the arcuate section.
 5. The method of claim 1,wherein the moving comprises translating the arcuate section.
 6. Themethod of claim 1, wherein the moving comprises moving the arcuatesection laterally with respect to an axis of the syringe.
 7. The methodof claim 1, wherein the moving comprises moving the arcuate sectiontoward the syringe by rotating the syringe in the first direction. 8.The method of claim 1, wherein the moving comprises pivoting the arcuatesection toward the syringe by rotating the syringe in the firstdirection.
 9. The method of claim 1, wherein the moving comprisestranslating the arcuate section toward the syringe by rotating thesyringe in the first direction.
 10. The method of claim 1, wherein themoving comprises moving the arcuate section laterally toward an axis ofthe syringe by rotating the syringe in the first direction.
 11. Themethod of claim 1, further comprising: contacting the syringe with aninside radius of curvature of the arcuate section as a result of therotation of the syringe in the first direction for the moving.
 12. Themethod of claim 1, wherein the arcuate section is substantiallysemicircular.
 13. The method of claim 1, wherein the spring forceprovided by the injector biases the arcuate section of the syringemounting mechanism toward an open position in which the syringe can bewithdrawn from an opening in the injector.
 14. The method of claim 1,wherein the spring force provided by the injector biases the arcuatesection toward an open position in which the arcuate section isdisengaged from the syringe.
 15. The method of claim 1, wherein thearcuate section pivots toward the syringe due to rotation of the syringein the first direction and away from the syringe due to rotation of thesyringe in the second direction substantially opposite the firstdirection.
 16. The method of claim 1, wherein the arcuate sectiontranslates toward the syringe due to rotation of the syringe in thefirst direction and away from the syringe due to rotation of the syringein the second direction substantially opposite the first direction. 17.The method of claim 1, wherein the spring force is oriented inopposition of syringe rotation in the first direction.
 18. The method ofclaim 1, wherein the spring force biases the arcuate section toward anopen position in which the arcuate section is disengaged from thesyringe.
 19. The method of claim 18, wherein, as a result of rotation ofthe syringe in the first direction relative to the injector, the arcuatesection is in a closed position in which the arcuate section is engagedwith the syringe.
 20. The method of claim 19, wherein, as a result ofrotation of the syringe in the second direction substantially oppositethe first direction, the arcuate section is in the open position. 21.The method of claim 1, wherein the moving comprises moving first andsecond arcuate sections of the syringe mounting mechanism relative tothe housing of the injector, and wherein the first arcuate sectioncomprises the arcuate section.
 22. The method of claim 21, wherein themoving of the first and second arcuate sections comprises pivoting eachof the first and second arcuate sections.
 23. The method of claim 21,wherein the moving of the first and second arcuate sections comprisestranslating each of the first and second arcuate sections.
 24. Themethod of claim 21, wherein the moving of each of the first and secondarcuate sections is in a direction substantially perpendicular to anaxis of the syringe.
 25. The method of claim 21, wherein the first andsecond arcuate sections are not integral with one another.
 26. Themethod of claim 21, wherein the moving of each of the first and secondarcuate sections, by rotating the syringe in the first direction, istoward an axis of the syringe.
 27. The method of claim 21, wherein themoving, by rotating the syringe in the first direction, occurs untilboth the first and second arcuate sections contact the syringe.
 28. Themethod of claim 21, wherein the spring force provided by the injectorbiases the first and second arcuate sections toward an open position inwhich the syringe can be withdrawn from an opening in the injector. 29.The method of claim 21, wherein the spring force provided by theinjector biases the first and second arcuate sections toward an openposition in which the first and second arcuate sections are disengagedfrom the syringe.
 30. The method of claim 21, wherein, as a result ofrotation of the syringe in the first direction relative to the injector,the first and second arcuate sections are in a closed position in whicheach of the first and second arcuate sections is engaged with thesyringe.
 31. The method of claim 30, wherein, as a result of rotation ofthe syringe in the second direction substantially opposite the firstdirection, the first and second arcuate sections are in the openposition.
 32. The method of claim 21, wherein each of the first andsecond arcuate sections is designed to move toward the syringe due torotation of the syringe in the first direction and away from the syringedue to rotation of the syringe in the second direction substantiallyopposite the first direction.
 33. The method of claim 32, wherein eachof the first and second arcuate sections is designed to pivot toward thesyringe due to rotation of the syringe in the first direction and awayfrom the syringe due to rotation of the syringe in the second directionsubstantially opposite the first direction.
 34. The method of claim 32,wherein each of the first and second arcuate sections is designed totranslate toward the syringe due to rotation of the syringe in the firstdirection and away from the syringe due to rotation of the syringe inthe second direction substantially opposite the first direction.
 35. Themethod of claim 32, wherein the spring force is oriented in oppositionof syringe rotation in the first direction.
 36. The method of claim 1,wherein the spring force is provided by first and second springs of theinjector.
 37. The method of claim 1, wherein the spring force isprovided by a torsion spring of the injector.
 38. The method of claim 1,wherein the spring force is provided by a coil spring of the injector.39. The method of claim 1, wherein the injector comprises a cam that isin contact with the syringe during the rotating, and the spring force istransferred via the cam to the syringe.
 40. The method of claim 39,wherein the cam pivots relative to the injector in response to therotating.
 41. The method of claim 1, wherein the rotating occurs whileat least a rearward end of a barrel of the syringe is located within anopening defined in the injector.
 42. The method of claim 41, wherein theopening is defined in a face plate of the injector.
 43. The method ofclaim 1, wherein the rotating occurs while at least a rearward portionof a barrel of the syringe is in contact with the injector and while aplunger of the syringe is substantially aligned with a drive ram of theinjector.
 44. A method of using a front-loading, medical fluid injector,the method comprising: rotating a syringe relative to the injector,wherein the rotating is accomplished in opposition to a spring forceprovided by the injector; and moving an arcuate section of a syringemounting mechanism of the injector relative to a housing of theinjector, wherein the moving is due, at least in part, to the rotating,and wherein the spring force provided by the injector biases the arcuatesection of the syringe mounting mechanism toward an open position inwhich the syringe can be withdrawn from an opening in the injector. 45.A method of using a front-loading, medical fluid injector, the methodcomprising: rotating a syringe relative to the injector, wherein therotating is accomplished in opposition to a spring force provided by theinjector; and moving an arcuate section of a syringe mounting mechanismof the injector relative to a housing of the injector, wherein themoving is due, at least in part, to the rotating, and wherein the springforce provided by the injector biases the arcuate section toward an openposition in which the arcuate section is disengaged from the syringe.